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1983 R80RT gas mileage

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Guaire
Posts: 34
Joined: Tue Aug 16, 2016 11:09 am

1983 R80RT gas mileage

Post by Guaire »

Got out on a Maryland state road for a ride last Thursday. The total length was 140 miles. I had added BG 44K fuel system cleaner to the fuel tank. Today I got gas. My mileage is 31 mpg.
The RT is performing well. Sometimes the idle will hang at about 2K rpm. Riding seems to be the cure for the hanging idle. Plugs are showing on the rich side. BP6ES plugs.
I have considered going to a DynaTek coil, but I'm not sure which one would work. Also, I don't know whether to use the resistance or non resistance wires, caps and plugs. I figure that a stronger spark would help the mileage.
I will check the valve gaps. I suspect they will be OK. Total miles on the bike is 23,800.
I would be appreciate any feedback.
Cheers,
Bill

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1983 R80RT, 2014 Royal Enfield Continental GT, 1986 Honda VF500F

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Twocams
Posts: 781
Joined: Sun Mar 16, 2014 8:42 pm

The plugs dont look to bad.

Post by Twocams »

The plugs dont look to bad. The right one maybe a little rich, but I wouldnt worry. You dont say how fast you were going. Or if you were using ethanol gas. Both of those can effect gas millage.
I went for a ride on my 92 other day with other guys. We were going 40-50 mph, 140 miles I got 40.75 MPG. And I was bored...last man.
Ethanol gas with additive for water control.


twocams
Twocams
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983
2015 Can Am Spider SE6 1,688 miles
2018 Moto Guzzi V711 Special

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schrader7032
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Not sure if you were running

Post by schrader7032 »

Not sure if you were running the fuel cleaner as part of the 140 mile run. It could reduce the volatility of the fuel, so could knock down the mileage. But an 800cc bike should do at least 10 if not 15 mpg more than that. Could be lots of things:

- valve clearances
- carb health and state of synching
- position of carb floats...they might be too high resulting in rich operation
- tire pressures
- final drive proper for the bike; RPMs might be higher than expected for given MPH

The stock ignition system should be just fine...I'd wait to throw money at this until you're sure of the state of tune. The bike should use zero resistance plugs and wires...the spark plug cap has a built-in 5K ohm resistance. Adding more resistance will make the spark weaker and it might misfire if the state of tune is marginal.

This page:

www.bmbikes.co.uk/specpages/R80RT.htm

suggests that the gas mileage should be in the low 40s.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

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Guaire
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I added the BG before the

Post by Guaire »

I added the BG before the ride. Riding speeds were from 40 to 60 mph. Using ethanol 10.
First thing I will do is check the valves. It's cheap. Then more after that.
Thanks,
Bill
1983 R80RT, 2014 Royal Enfield Continental GT, 1986 Honda VF500F

khittner
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If this was the first time

Post by khittner »

If this was the first time you filled the gas tank after a winter lay-up, your fuel tank probably wasn't full to begin with, even if you had filled it when you put it away last Fall. There can be a non-trivial amount of fuel evaporation over the course of 5 months or so.
Konrad

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Guaire
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Got the valves

Post by Guaire »

Got the valves checked/adjusted. Left intake had zero clearance. L Ex was OK. Adjusted the Rights. Got out for a 50 mile run. Mileage went up to 31.9 mpg. Looks like it’s carb check time. It doesn’t feel like they are out of balance. When I stop, the motor goes to 2k rpm, then settles down to 1400 @ rpm. That bothers me.
Is there a connector for a carb sync on my Bings?
I saw the spec online. Informative.
I kept the bike running through the winter. I had a good tank of gas for my little trip. 91 octane, fresh.
EUBMW in Alexandria, VA has carb kits. I’ll want to see if anything is obviously amiss before I buy anything. Yes, I should check the float height.

Thanks,
Bill

https://www.eubmw.com/collections/carbu ... uretor-kit
1983 R80RT, 2014 Royal Enfield Continental GT, 1986 Honda VF500F

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schrader7032
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With the idle RPM so high, it

Post by schrader7032 »

With the idle RPM so high, it does sound like you need to do a carb overhaul and a synch. The carbs should have vacuum takeoff ports which lets a differential pressure device like a TwinMax attach. Here's a picture of the port on the side of my carb on my /7...the '83 port might be underneath.
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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

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Guaire
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Joined: Tue Aug 16, 2016 11:09 am

Thanks, Kurt. I’ll get after

Post by Guaire »

Thanks, Kurt. I’ll get after the carb situation. At least I don’t have to overhaul 4 of them.

Bill
1983 R80RT, 2014 Royal Enfield Continental GT, 1986 Honda VF500F

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Twocams
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Another thing is the Governor

Post by Twocams »

Another thing is the Governor weights inside the "can" hanging up? Oak had talked about them in one of the Airmail Magazines.

twocams
Twocams
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983
2015 Can Am Spider SE6 1,688 miles
2018 Moto Guzzi V711 Special

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Guaire
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Two cams - "Another thing

Post by Guaire »

Two cams -
"Another thing is the Governor weights inside the "can" hanging up? Oak had talked about them in one of the Airmail Magazines."

I thought my ignition was electronic. Does the weights problem still apply?

Bill
1983 R80RT, 2014 Royal Enfield Continental GT, 1986 Honda VF500F

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